Memory devices are typically provided as internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including volatile and non-volatile memory. Volatile memory can require power to maintain its data and includes random-access memory (RAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM), among others. Non-volatile memory can provide persistent data by retaining stored information when not powered and can include NAND flash memory, NOR flash memory, read only memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and phase change random access memory (PCRAM), among others.
Memory devices can be combined together to form a solid state drive (SSD). A solid state drive can include non-volatile memory, e.g., NAND flash memory and NOR flash memory, and/or can include volatile memory, e.g., DRAM and SRAM, among various other types of non-volatile and volatile memory.
An SSD can be used to replace hard disk drives as the main storage device for a computer, as the solid state drive can have advantages over hard drives in terms of performance, size, weight, ruggedness, operating temperature range, and power consumption. For example, SSDs can have superior performance when compared to magnetic disk drives due to their lack of moving parts, which may avoid seek time, latency, and other electromechanical delays associated with magnetic disk drives. SSD manufacturers can use non-volatile flash memory to create flash SSDs that may not use an internal battery supply, thus allowing the drive to be more versatile and compact.
An SSD can include a number of memory devices, e.g., a number of memory chips (as used herein, “a number of” something can refer to one or more of such things, e.g., a number of memory devices can refer to one or more memory devices). The collection of memory devices on an SSD can be referred to as a memory unit. As one of ordinary skill in the art will appreciate, a memory chip can include a number of dies. Each die can include a number of memory arrays and peripheral circuitry thereon. The memory arrays can include a number of memory cells organized into a number of physical blocks, and the physical blocks can be organized into a number of pages.
Some format utilities may be unaware of the physical characteristics of the memory arrays that make up an SSD. Thus, when an SSD is formatted with such a utility for a particular file system, the memory unit may be divided into a number of areas, each having a starting logical address that may or may not correspond to a physical boundary such as a page or block of memory cells. For example, a user data area of the file system may have a starting logical block address that can map to the middle of a page or block of memory cells.